The objective of this proposal is to maintain a closed specific pathogen-free (SPF) rhesus macaque supply and breeding colony program at the Sabana Seca Field Station of the Caribbean Primate Research Center (CPRC). The founding stock of genetically-characterized Indian-origin monkeys donated by CPRC will consist of approximately 755 SPF (Herpes B, STLV-1, SIV and SRV-free) rhesus macaques of which 164 (or 22%) will also be free of the papova virus SV40. Thus, this colony will consist of two SPF sub colonies: one SV40-free and the other SV40 positive. Animals from these two closed SPF sub colonies will be housed in reproduction corncribs, and will be quarterly tested for the presence of the above mentioned target viruses. A panel of highly polymorphic genetic markers will be used to characterize the colony and to optimize the structure of breeding groups, maximizing the level of their genetic heterogeneity. By year five, the program will produce a total estimated offspring of 1,082 SPF rhesus macaques, of which 301 will be also SV40 negative. These SPF macaques will help meet the increased research demand for these animals. At the end of this 5 year grant, it is expected that this program will produce more than 160 animals/year and will attain self-sufficiency. CPRC will continue to make significant contributions to AIDS and to other research programs by providing high quality and healthy SPF rhesus monkeys to NIH-sponsored research initiatives.